1. Field of the Invention
This invention relates to a multi-turn absolute encoder capable of measuring the turning angles of one or more turns, for example, of a rotating shaft; and more particularly, to such an encoder which is capable of operating even when power is cut off and which is capable of invariably obtaining absolute measurement outputs.
2. Description of the Prior Art
A typical prior art multi-turn absolute encoder uses a speed reduction gear mounted on a rotary shaft with the turning angle being measured by an absolute encoder or a potentiometer after deceleration has been effected.
However, there are some drawbacks to this type of multi-turn absolute encoder. For example, the device undergoes backlash influences, or the like, because mechanical rotation propagating units, such as the speed reduction gear, are provided. This in turn makes highly accurate measurement highly unlikely. Also, this necessitates use of an intricate and complicated structure. As a result, reliability is decreased.